A demodulation reference symbol (DM-RS) may be provided for channel estimation for coherent demodulation. DM-RSs may be associated with physical uplink shared channel (PUSCH) data and/or physical uplink control channel (PUSCCH) control transmission. DM-RSs may be present in every transmitted uplink time slot.
FIG. 2A is a diagram of a prior art mapping of DM-RS transmission in a subframe with a normal cyclic prefix. FIG. 2B is a diagram of a prior art mapping of DM-RS transmission in a subframe with an extended cyclic prefix. FIG. 2C is a diagram of a prior art mapping of DM-RS transmission amongst subcarriers in a subframe with a normal cyclic prefix. A DM-RS may be mapped to an orthogonal frequency-division multiplexing (OFDM) symbol of each time slot. As shown in FIG. 2A, for normal cyclic prefix, the DM-RS may be mapped to the fourth OFDM symbol of each time slot. As shown in FIG. 2B, for extended cyclic prefix, the DM-RS may be mapped to the third OFDM symbol of each time slot. As shown in FIG. 2C, the DM-RS may be mapped to every subcarrier of an OFDM symbol for which it is mapped.